397　it和one 替代普通名词时的区别

① it代替已经提到过的特指单数可数名词，两者为同一物。

As this chair is broken，I must have it repaired. 这张椅子坏了，我得叫人修理一下。

My father bought a pen and gave it to me. 我父亲买了一支钢笔，给我了。

A：Do you need the book？你需要这本书吗？

B：Yes，I need it. 对，我需要（它）。

② one用以代替已经提过的泛指单数的可数名词，但one和已提过的名词不是同一物。

我的伞丢了，我得买一把。

I have lost my umbrella and I must buy it.

I have lost my umbrella and I must buy one.

I have no dictionary，so I want to buy one. 我没有词典，所以想买一本。

A：Do you need a bike？你需要一辆自行车吗？

B：Yes，I need one. 是的，我需要一辆。

③ 另外，it可以代替不可数名词，而one只能代替可数名词单数。

The wine is too strong，so I can't drink it. 这是度数太高的烈性酒，所以我不能喝。

This wine is milder than that. 这种酒比那种酒要淡。（不可用 than that one）